FOUR men have been arrested following an assault at the weekend.A 47-year-old man, from Stoke-on-Trent, sustained serious head injuries during the incident outside the Black Lion pub, on London Road, in Trent Vale, at 9.20pm on Saturday.The man was taken to the University Hospital of North Staffordshire where he remains in a stable condition.The arrested men, aged 32, 33, 34 and 36, all from Stoke-on-Trent, have been bailed, pending further inquiries to a date in March.Staffordshire Police has now launched an appeal for witnesses and is urging anyone with information to come forward.Witnesses should contact DC Rob Booth at Staffordshire Police on 101 quoting incident number 664 of January 12, or Crimestoppers anonymously on 0800 555 111.